JPS61103967A - Coating solution - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to coating solutions containing organosilicon compounds that can be converted to SiO2 by heat treatment. Such a coating solution can be used when the surface of an object is to be coated with a layer of SiO□. In this case, the coating solution is applied as a thin film of solution to the substrate surface to be coated. After drying, the organosilicon compound is then converted into SiO by a heat treatment step.
can be almost or completely converted to 2. Well-known applications include optical glasses such as lenses, special optics, translucent optical mirrors, fiber optic cables, ophthalmic lenses, insulating glass for windows, etc., where such coatings are sensitive to the effects of the environment. , humidity, protection from aggressive substances or a change in the refractive index can be achieved. Furthermore, SiO2 layers formed using such solutions can be used as insulating, interlayer or protective layers in electronic circuits, in particular integrated semiconductor components or their production.

In a particular aspect, the present invention provides a photostructurable multilayer resist system for structuring semiconductor substrates in the manufacture of highly integrated electronic circuits that is substantially SiO2 and oxygen plasma resistant. Regarding layers.

As is well known, circuit structures are transferred to semiconductor articles by using high-resolution photolithography, or sometimes by using a series of such methods, and ultimately form semiconductor components, ``chips.'' ” is completed.

The continued miniaturization of electronic circuits, with the goal of increasingly higher circuit densities and integration densities for current chips, requires the ability to reproduce fine and hyperstructures in the micron and sub-micron range. Therefore, extremely stringent requirements regarding reproduction fidelity must be met by the photoresist systems and working techniques used here. However, with current techniques of coating a substrate with a layer of photoresist, photostructuring by imagewise exposure, and then developing the photoresist relief structure, this fidelity depends on one hand on optical parameters (wavelength of the radiation used, optical projection system, etc.). quality) from K and on the other hand,
Line widening, resist edge bending and rounding, and layer wear caused by isotropic wet development, as well as plasma etching (reactive ion etching, RIE)
The structural changes on the photoresist image that occur in the increasingly used almost anisotropically proceeding dry development methods, such as , are limited by the attendant high heat loads and increased layer wear.

In accordance with the current state of technology, multilayer resist-based techniques have been used only recently to ensure the highest reproduction fidelity and resolution in the micron and submicron range for the structures when producing extremely fine structures. There is.

For example, in a three-layer resist system, a thin intermediate layer resistant to oxygen plasma and consisting of an inorganic material, usually substantially SiO2, is applied over a basecoat layer coated onto a semiconductor substrate.

It is. Above this intermediate layer is a thin layer of photoresist. To create an image pattern on the semiconductor surface, the photoresist layer is conventionally exposed and developed. Dimensional changes to the resist image result in smaller dimensional changes compared to single layer techniques. The exposed areas of this inorganic interlayer can then be removed by plasma etching in a fluorine-containing medium. In this way, the resist image is transferred with very high precision. In a subsequent plasma etching process using an oxygen-containing plasma, the substrate surface is exposed with high fidelity in the area of the thus created "resist window" and the remaining portions of the resist coating are simultaneously oxidized. removed. Thereafter, functionalization of the circuitry in the exposed areas of the semiconductor substrate can be carried out in known manner by etching, doping or coating with metal, semiconductor material or insulating material.

The current state of the art in multilayer resist technology is illustrated and described in detail in European Publication No. 0,114,229 A2 and in the series of interrogatories and patent documents listed therein.

In multilayer resist techniques, the inorganic interlayer is the most important.

The intermediate layer serves as a passivation or protective layer in the final plasma etching step to prevent plasma oxygen attack on areas of the basecoat layer that are not to be removed.

For this purpose, an intermediate layer must on the one hand be resistant to oxygen plasma and, on the other hand, be removable by a correspondingly different etching plasma and capable of forming image structures. .

There must be. Furthermore, good adhesion to both the basecoat layer and the overlying photoresist layer must be ensured during the entire processing step. The resistance of the interlayer to wet development for photoresists is also of particular importance.

According to the European publication, the intermediate layer is formed by a plasma polymerization method in which a plasma is charged with a variety of organosilicon compounds. In this case, an organosilicon compound layer is formed on the basecoat layer, which is not defined in detail and which must be subsequently heat-treated at a temperature of approximately 600.degree. Such a coating can be etched by a fluorine-containing plasma. In oxygen plasma, this interlayer has a deactivating effect on the plasma oxygen by "burning" of the organic functions present in it, and also a deactivation effect on the underlying basecoat layer by the SiO2 thus formed. Has a protective effect. Although relatively good results can be obtained with this system, it still has significant drawbacks. On the one hand, the production of intermediate layers by plasma polymerization is complex, requires expensive equipment and is therefore expensive. On the other hand, the basecoat layer is exposed to high thermal loads during the plasma deposition process of the organosilicon polymer and during the subsequent heat treatment. Not all materials that can be used as base coats can withstand temperatures of about 300° C. or higher without damage. The basecoat layer is typically heat treated as well to improve its adhesion to the substrate, although the temperatures used for this purpose generally rarely exceed 200'C. Therefore, significantly high temperatures occurring during the manufacture of the interlayer can cause the loss of volatile components contained in the basecoat layer, decomposition of the basecoat, or other undesirable changes. This jeopardizes the good and uniform adhesion of the intermediate layer; fine cracks and pores may form in the intermediate layer) or it may become partially peeled off or completely unusable.

Other methods have been disclosed for producing such protective layers from inorganic materials, such as chemical vapor deposition (CVD) and deposition using thermionic discharge or cantos batter. However, these methods also require expensive equipment and impose high thermal loads on the basecoat layer.

Preparation of these layers using coating solutions containing organosilicon compounds that can be converted to S 102 5. .

This method is very advantageous because it is very simple to implement. Such solutions are known, for example, from glass coating technology.

These are in most cases aqueous-alcoholic solutions in which tetraalkylorthosilicate compounds are used as organosilicon compounds which can be converted into 5io2. Coatings produced using such solutions can be almost completely converted to SiO2 by heat treatment.

However, in our experiments, we have found that the temperatures required for this purpose are still unreasonably high for use in multilayer resist techniques. Hatondo 5IO2
Although better layers are obtained by heat treatment at moderate temperatures around about 200°C, these have not proven to be reasonably resistant to developer solutions for photoresist coatings.

It is therefore an object of the present invention to develop a coating solution for producing layers which are substantially similar to SiO2, which can be heat processed at temperatures suitable for multilayer resist techniques, and which are sufficiently stable to photoresist developers. It happened to me.

Here, a coating solution based on an alcoholic solution of an organosilicon compound that can be converted to jJs102 by heat treatment is added to these solutions with a tetraalkyl orthosilicate compound, a vinyltrialkoxysilane compound, or a vinyltriacyloxysilane compound and It has been found that the use of mixtures obtained from (or) gamma-glycidoxypropyltrialkoxysilane compounds is particularly suitable for the production of inorganic interlayers in multilayer resist technology. Layers formed from such solutions can be moderately heat-processed at temperatures around 200°C; furthermore, they are sensitive to photoresist developers, especially aqueous-alkaline developers for positive-working photoresists. It is exceptionally stable.

Therefore, the present invention is based on an alcoholic solution of an organosilicon compound that can be converted into SiO□ by heat treatment, and a tetraalkyl orthosilicate compound, a vinyltriazyloxysilane compound, or a vinyltriacyloxysilane compound and/or r - Coating solutions containing mixtures obtained from glycidoxypropyltrialkoxysilane compounds.

The present invention also provides such a coating solution for SiO2
The present invention relates to use as a coating solution for the production of layers of substantially different types.

Furthermore, the present invention provides a coating solution containing an organosilicon compound that can be converted into 98to2 by heat treatment, and then heat-treating to obtain S
A method for producing a layer consisting essentially of iO2 using a coating solution according to the invention.

In particular, the present invention applies a basecoat layer on which an interlayer that is substantially SiO2 and is resistant to oxygen plasma is used for coatings containing organosilicon compounds that can be converted to SiO2 by heat treatment. A method of coating a semiconductor substrate surface with a photostructural multilayer resist system comprising the application of a photoresist layer after coating with a solution and subsequent heat treatment, the method comprising: applying a photoresist layer using a coating solution according to the invention; Regarding the law.

Furthermore, the present invention uses a photostructural multilayer resist system consisting of a basecoat layer, an interlayer consisting essentially of SiO2 and resistant to oxygen plasma, and a photoresist/li, and imagewise exposing the photoresist layer. A method for structuring a semiconductor material by developing and removing exposed areas of the SiO2 intermediate layer by plasma etching with a fluorine-containing plasma, and then removing exposed areas of the resulting base coat layer by plasma etching with an oxygen plasma, comprising: , relates to a method for forming an intermediate layer of this multilayer resist system by coating with a coating solution according to the invention.

In each component constituting the mixture of organosilicon compounds used in the coating solution according to the invention, the alkyl, alkoxy or acyl groups can each be the same or different and have from 1 to 5 C atoms. can.

All suitable straight-chain or branched groups can be used.

Preferably, the specific groups in each component, tetraalkyl, orthosilicate compound, vinyltrialkoxysilane compound or vinyltriacyloxysilane compound and γ-glycidoxypropyltrialkoxysilane compound are the same. In particular, from the viewpoint of good availability, compounds whose alkyl is methyl, ethyl, n-4 or 1-propyl are preferred among the tetraalkyl orthosilicates. The same applies to vinyltrialkoxysilane compounds and gamma-glycidoxypropyltrialkoxysilane compounds, the alkoxy groups in these compounds being preferably groups derived from said alkyl groups. In the vinyltriacyloxysilane compound, the acyloxy group is preferably an acetoxy or propionyloxy group. % preferred ingredients are tetramethylorthosilicate, tetraethylorthosilicate, vinyltrimethoxysilane, vinyltriethoxysilane, r-glycidoxypropyltrimethoxysilane and gamma-glycidoxypropyltriethoxysilane.

All compounds of this type are commercially available or can be easily prepared by standard methods.

The mixture used in the coating solution according to the invention is a binary mixture of tetraalkylorthosilicate and vinyltrialkoxysilane or vinyltriazyloxysilane/or tetraalkylorthosilicate and γ-glycidoxypropyltrialkoxysilane. can be. However, it is likewise possible to choose a tetraalkylorthosilicate, a vinyltrialkoxysilane or a six-component mixture of vinyltriacyloxysilane and γ-glycidoxypropyltrialkoxysilane.

In the case of a binary mixture, the ratio of tetraalkylorthosilicate and vinyltrialkoxysilane or vinyltriacyloxysilane, or tetraalkylorthosilicate and γ-glycidoxypropyltrialkoxysilane is 1:0.2 to 10, preferably 1:1. : Exists in a molar ratio of 1 to 5. In the case of ternary mixtures, the tetraalkyl orthosilicate, vinyltrialkoxysilane or vinyltriacyloxysilane and r-glycidoxypropyltrialkoxysilane are used in a ratio of 1:0.2 to 5:0.
It can be used in a molar ratio of 2 to 5.

To prepare the coating solution according to the invention, a suitable organosilicon compound is mixed with or dissolved in an alcoholic solvent. Alcoholic solvents that can be used include, in particular, lower aliphatic alcohols, which can be used alone or in mixtures. In particular these solvents can be methanol, ethanol, n- or 1-propanol and n-butanol. Solvent mixtures of methanol or ethanol and n- or l-i lobanol or n-butanol have proven suitable.

Coating solutions according to the invention can also contain small amounts of water. The water content generally ranges from 1 to 10% by weight, preferably about 5% by weight of the total weight of the ready-to-use coating solution.

The organosilicon compound is 0101 to 1 mol/t of the final solution.
% is preferably used in the coating solution in a total content of 0.05 to 0.2 mol/l.

In the coating solutions according to the invention, the organosilicon compounds can be present in added form.

However, it is advantageous if the organosilicon compound is hydrolyzed more or less completely during the preparation of the coating solution. This can be accomplished by adding a catalytic amount of a contributing acid, preferably nitric acid, and then heating the coating solution, preferably after mixing all ingredients. As a catalytic amount of acid,
Addition amounts of 0.01 to 0.1% by weight of pure or concentrated acid, based on the total amount of coating solution, are sufficient. Primarily, organic groups bonded to silicon via oxygen are used in this process.

Hydrolytically separated from ion compounds. This gives a somewhat organically modified silica sol, in which the remaining organic moieties are mainly the vinyl and/or r-glycidoxypropyl groups of the organosilicon compounds used.

It is believed that a particularly advantageous property of the coating solution according to the invention when used in multilayer resist technology is that the modified silica sol is produced in this way. clearly,
It is primarily important here that the predetermined vinyl and/or glycidoxypropyl groups are contained in a controlled manner by the mixture of organosilicon compounds used.

The coating solution according to the invention can be used in all cases where coatings consisting entirely of K or essentially of SiO2 are to be formed. These solutions are particularly advantageous if the lowest usable heating temperature is desired or absolutely required for the formation of the SiO2-containing layer.

To form such a layer, a coating solution is applied to a particular substrate using conventional coating techniques. If necessary, the concentration of the solution can be adapted to the particular purpose beforehand by further dilution or by concentration. After bubbling off the solvent or drying by heating if necessary, the resulting layer then has a
Heat treatment can be carried out at 250°C, preferably about 200°C, but higher temperatures if necessary. This process is generally completed within several minutes, typically 2 to 5 minutes. When using the coating solution according to the invention, a layer consisting essentially of SiO2 of 180 to 200 tl
It is found that it can be obtained even by heat treatment at temperatures of :. These eyebrows are smooth, exhibiting a dense surface and are uniform throughout the layer thickness without indentations or holes.

Due to these advantageous properties, the coating solution according to the invention becomes substantially more effective than SiO2 in multilayer resist techniques for the photolithographic formation of fine and highly precise structures on semiconductor materials. It is particularly suitable for forming intermediate layers that are resistant to plasma.

In the method according to the invention for coating and structuring the surface of a semiconductor substrate using a multilayer resist system, the substrate is first coated with a base coat layer by conventional coating methods. The thickness of this layer can be selected approximately in the range from 1 to 20 μm. Layer thicknesses of 1 to 6 μm have proven suitable. In principle, all coating systems customary in resist and semiconductor technology are suitable for priming.

In a preferred embodiment of the invention, the base coat used can be a positive-working photoresist composition that is subsequently used as a top photostructuring photoresist layer. After a customary heat treatment step at a temperature of about 200° C. for curing and improving adhesion, the coating solution according to the invention is preferably applied by the spin-coating method.

The layers are applied in such a way that a layer thickness of 50 to 300 nm is obtained. For the intended purpose, layer thicknesses of 100 to 250 nm have proven particularly advantageous. Suitable coating techniques and the processing parameters that must be envisaged for the desired layer thickness are well known to those skilled in the art. A heat treatment is then carried out under the conditions described above.

A practical photostructural resist layer is then applied. In principle, all customary positive-working or negative-working photoresist compositions can be used for this purpose. Positive-working photoresist compositions are preferred, especially those of the O-quinone-diazide/novolak resin type. To enable the highest possible reproduction fidelity and resolution, photoresist materials should be used at the lowest possible layer thickness. 0.3~1
A layer thickness of 1 .mu.m, in particular about 0.5 .mu.m, has proven advantageous. Prior to performing the photostructuring process, the photoresist layer can also be subjected to a conventional heat treatment step.

The production of photoresist relief structures on semiconductor substrates using such multilayer resist systems uses methods known per se. Imagewise expose the top resist layer; positive 1. .

In the case of active photoresist materials, the exposed image areas of the resist layer are removed by development with a conventional aqueous-alcoholic developer solution. For this purpose, either alkali metal ion-containing or alkali metal ion-free developers are used. The thus exposed areas of the interlayer formed using the coating solution according to the invention are resistant to this development treatment and do not suffer any visible damage. Plasma etching using a fluorine-containing plasma (the type of equipment used here and the process conditions used are known to those skilled in the art) removes the intermediate layer under the "resist window" and exposes the exposed areas of the base coat to an oxygen plasma. is removed from the substrate surface by further performing a plasma etching process.

During this step, the interlayer mask obtained in the previous processing step effectively protects the underlying basecoat from attack by plasma oxygen.

Using such multilayer resist systems, fine and highly precise structures can be transferred to semiconductor substrates with the highest precision. Here, the coating solution according to the invention features a stable and highly effective intermediate layer that is resistant to oxygen plasma.

serves as an excellent auxiliary material for simple formation.

Example Preparation of coating solution: 1. Preparation of coating solution from the following ingredients: Ethanol 627 In-Butanol
100.9 Tetraethyl orne silicate 81 Vinyltriethoxysilane 14
3I Nitric acid (1%) 47I 2. Prepare the coating solution from the following ingredients: Ethanol 5661 n-Butanol
100I tetraethyl orthosilicate 40J? Nitric acid (1%) 5
1 [3. Manufacture a coating solution from the following ingredients:
Methanol 400In-propertool 266I Tetraethyl orthosilicate 40! j Nitric acid (1%)
5014, prepare a coating solution from the following ingredients: ethanol 627gn-butanol ioo! i Tetrapropylorthosilicate 83.9 Vinyltriethoxysilane 143I Nitric acid (1 yen)
47I5, prepare a coating solution from the following ingredients: ethanol 6271 n-butanol 100I tetraethyl orthosilicate 83.5'vinyltriacetoxysilane 143.9 nitric acid (1%)
47I The components of the particular coating bath described above are mixed together and the resulting mixture is heated at reflux temperature for 8 hours. After cooling and microfiltration, these coating solutions are ready for use.

Claims (8)

[Claims] (1) Based on an alcoholic solution of an organosilicon compound that can be converted to SiO_2 by heat treatment, tetraalkylorthosilicate (the alkyl group has 1 to 5 C atoms), vinyltrialkoxysilane or vinyltri obtained from acyloxysilanes (the alkoxy or acyloxy group has 1 to 5 C atoms) and/or γ-glycidoxypropyltrialkoxysilanes (the alkoxy group has 1 to 5 C atoms) Coating solution containing the mixture. (2) A coating according to claim 1, in which the tetraalkylorthosilicate and vinyltrialkoxysilane or vinyltriacyloxysilane are used in a molar ratio of 1:0.2 to 10, preferably 1:1 to 5. solution. (3) Tetraalkylorthosilicate and γ-glycidoxypropyltrialkoxysilane at 1:0.2
Coating solution according to claim 1, used in a molar ratio of from 1:1 to 10, preferably from 1:1 to 5. (4) A claim in which tetraalkylorthosilicate, vinyltrialkoxysilane or vinyltriacyloxysilane and γ-glycidoxypropyltrialkoxysilane are used in a molar ratio of 1:0.2 to 5:0.2 to 5. Coating solution according to scope 1. (5) The total content of the organosilicon compounds is from 0.01 to
Coating solution according to claim 1, having a concentration of 1 mol/l, preferably from 0.05 to 0.2 mol/l. (6) A coating solution containing an organosilicon compound that can be converted into SiO_2 by heat treatment is applied to the substrate surface, and then heat treatment is applied to substantially convert SiO_2 into SiO_2.
This method uses as a coating solution an alcoholic solution of an organosilicon compound that can be converted into SiO_2 by heat treatment as a base material, and uses a tetraalkyl orthosilicate (this alkyl group has 1 to 5 atoms) as a base material. (having C atoms), vinyltrialkoxysilanes or vinyltriacyloxysilanes (the alkoxy or acyloxy group having 1 to 5 C atoms) and (
or) γ-glycidoxypropyltrialkoxysilane (the alkoxy group has 1 to 5 C atoms)
A method characterized in that it uses a coating solution containing a mixture obtained from. (7) Applying a basecoat layer and coating on this basecoat layer an interlayer, which is more substantial than SiO_2 and resistant to oxygen plasma, with a coating solution containing an organosilicon compound that can be converted to SiO_2 by heat treatment. A method of coating the surface of a semiconductor substrate with a photostructure-forming multilayer resist system by applying a photoresist layer after forming the intermediate layer by applying a photoresist layer after heat treatment, the method comprising: forming an intermediate layer using SiO_2 as a coating solution by heat treatment; Based on alcoholic solutions of organosilicon compounds that can be converted into has 1 to 5 C atoms) and/or
A method for coating semiconductor substrate surfaces, characterized in that a coating solution containing a mixture obtained from γ-glycidoxypropyltrialkoxysilanes (the alkoxy group having 1 to 5 C atoms) is used. . (8) Using a photostructural multilayer resist system consisting of a basecoat layer, an interlayer consisting essentially of SiO_2 and resistant to oxygen plasma, and a photoresist layer, imagewise exposing the photoresist layer and then developing it. ,
S by plasma etching using fluorine-containing plasma
A method for structuring a semiconductor substrate by removing exposed regions of the iO_2 intermediate layer and then removing exposed regions of the resulting base coat layer by plasma etching with oxygen plasma, the method comprising heating the multilayer resist-based intermediate layer. Based on alcoholic solutions of organosilicon compounds that can be converted to SiO_2 by the acyloxy group has 1 to 5 C atoms) and/or γ
- semiconductors, characterized in that they are formed by coating with a coating solution containing a mixture obtained from glycidoxypropyltrialkoxysilanes, the alkoxy groups having from 1 to 5 C atoms, and then heated. A method of forming a structure on a substrate.